1. Field of the Invention
The present invention relates to an apparatus for sterilizing cartons made of laminated material comprising paper layers, plastics layers or metal layers, and designed to contain and preserve milk, fruit juice, or the like for a long period of time. More particularly, the invention relates to an apparatus for sterilizing sleeve-shaped cartons made by cutting a tubular, laminated packaging material into pieces of a predetermined length.
2. Description of the Related Art
Cartons for containing and preserving milk, fruit juice, or the like for a long time are made of laminated material comprising paper layers, plastics layers or metal layers. In most cases, the cartons are manufactured in the following manner. First, a tube of laminated packaging material is cut into some pieces, each being a sleeve-shaped member opening at both ends. Next, the sleeve-shaped member are sterilized. Each of these sleeve-shaped members is heated, only at one end portion. Then, this end portion is folded, sealed, and closed, thereby forming a carton having a flat, closed bottom. Thereafter, the carton is filled with milk, fruit juice, or the like, and the top portion of the carton is closed and sealed.
Generally, the process of sterilizing the sleeve-shaped carton consist of two steps. In the first step, solution of hydrogen peroxide is sprayed into and over the sleeve-shaped carton, thereby sterilizing both the inner surface and the outer surface of the carton. In the second step, hot air is applied into and over the carton, thus drying the carton.
In some cases, an additional sterilizing process is carried out after one end of the sleeve-shaped carton has been heated, folded, sealed, and closed. More precisely, the sterilizating solution is sprayed into and over the carton, now having a flat, closed bottom, and hot air is applied into and over the carton, while the carton is being moved on an endless chain-belt to the next station where the carton will be filled with milk, fruit juice, or the like.
The sterilizing process described above has a problem. The sterilizating solution cannot sprayed uniformly into or over the carton, or in a sufficient amount. As a consequence, the carton cannot be sterilized completely. In order to be sterilized completely, the carton may be immersed into a bath of the solution. This method indeed ensures complete sterilization, but makes it difficult to remove the sterilizing solution perfectly from the carton by means of the hot-air drying. There is the possibility that some solution remain in the inner surface of the carton.
Accordingly, it is the object of the present invention to provide a sterilizing apparatus which can completely sterilize cartons for containing drinks, and can also remove a sterilizing solution from the cartons completely.